Final answer:
Non-native species that are able to establish themselves and thrive in a new ecosystem, lacking natural predators, are known as invasive species. They can out-compete native species for resources and fundamentally alter ecological conditions, leading to negative impacts on native species and sometimes even extinctions.
Step-by-step explanation:
Non-native species that successfully establish themselves in a new ecosystem often lack natural predators in their new environment. This can lead to their populations growing exponentially, allowing them to sometimes out-compete and threaten the existence of native species. When non-native species survive and start to affect the native ecosystem by competing for resources, predating on native species, or introducing diseases, they become known as invasive species.
Invasive species can have detrimental effects, resetting the ecological conditions in their new habitat and causing extinctions of native species. The introduction of non-native species can be through human actions, either intentionally, such as for trade, or unintentionally, such as through human transportation. Successful invasive species may have pre-adaptations that make them particularly fit for their new environment, or they might experience a population boom because they are no longer held in check by the predators, competitors, and diseases present in their native habitat.